This invention relates generally to alarm units, and more particularly to improvements in pool or spa alarms.
Examples of such units, and related units, are found in the following U.S. Pat. Nos.: 3,054,096 to Pertiz, 3,683,353 to Miller, 3,786,469 to Massaro, 3,636,544 to Codina, 3,953,843 to Codina, 3,359,550 to Christensen, 3,778,803 to Jahn, 4,069,405 to Fima, 3,276,007 to White, 3,038,151 to O'Connor, 4,333,094 to Osborne,
Such prior units are undesirably complex or impractical in construction, circuitry and modes of operation, and/or results, so that there is need for a simple, practical unit which will meet the needs for pool or spa safety, i.e. provide an alarm when a surface wave is produced.